I. Field
The present invention relates generally to communication, and more specifically to a modulator/demodulator (modem) for a communication system.
II. Background
In a wireless communication system, a transmitter processes data to generate a radio frequency (RF) modulated signal and transmits the RF modulated signal on a frequency channel via a wireless communication link to a receiver. The transmitted signal is distorted by the wireless link (e.g., fading and multipath), corrupted by noise, and further degraded by interference from other transmitters transmitting on or near the same frequency channel. The receiver receives the transmitted signal, processes the received signal, and attempts to recover the data sent by the transmitter. The distortion due to the wireless link, the noise, and the interference all hinder the receiver's ability to recover the transmitted data.
The receiver is typically designed such that it can meet various system requirements under the worst case operating conditions. This typically entails designing filters and other circuit blocks such that the desired performance can be achieved even if the RF modulated signal is received at the lowest specified level and the interfering signal is at the highest specified level. This conventional receiver design has certain key limitations, as described below.